linux-kernel - Re: [Linux-kernel-mentees][PATCH v4 1/1] sgi-gru: Remove *pte

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Date:   Thu, 8 Aug 2019 16:30:48 -0700
From:   John Hubbard <jhubbard@...dia.com>
To:     Bharath Vedartham <linux.bhar@...il.com>, <arnd@...db.de>,
        <gregkh@...uxfoundation.org>, <sivanich@....com>
CC:     <ira.weiny@...el.com>, <jglisse@...hat.com>,
        <william.kucharski@...cle.com>, <hch@....de>,
        <linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
        <linux-kernel-mentees@...ts.linuxfoundation.org>
Subject: Re: [Linux-kernel-mentees][PATCH v4 1/1] sgi-gru: Remove *pte_lookup
 functions

On 8/8/19 4:21 PM, John Hubbard wrote:
> On 8/8/19 11:55 AM, Bharath Vedartham wrote:
> ...
>>  	if (is_gru_paddr(paddr))
>>  		goto inval;
>> -	paddr = paddr & ~((1UL << ps) - 1);
>> +	paddr = paddr & ~((1UL << *pageshift) - 1);
>>  	*gpa = uv_soc_phys_ram_to_gpa(paddr);
>> -	*pageshift = ps;
> 
> Why are you no longer setting *pageshift? There are a couple of callers
> that both use this variable.
> 
> 

...and once that's figured out, I can fix it up here and send it up with 
the next misc callsites series. I'm also inclined to make the commit
log read more like this:

sgi-gru: Remove *pte_lookup functions, convert to put_user_page*()

For pages that were retained via get_user_pages*(), release those pages
via the new put_user_page*() routines, instead of via put_page() or
release_pages().

This is part a tree-wide conversion, as described in commit fc1d8e7cca2d
("mm: introduce put_user_page*(), placeholder versions").

As part of this conversion, the *pte_lookup functions can be removed and
be easily replaced with get_user_pages_fast() functions. In the case of
atomic lookup, __get_user_pages_fast() is used, because it does not fall
back to the slow path: get_user_pages(). get_user_pages_fast(), on the other
hand, first calls __get_user_pages_fast(), but then falls back to the
slow path if __get_user_pages_fast() fails.

Also: remove unnecessary CONFIG_HUGETLB ifdefs.

thanks,
-- 
John Hubbard
NVIDIA